US5162815A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal printing apparatus with tensionless donor web during printing
Assignee: Eastman Kodak Co
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Filing: 1992-04-13
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Granted: 1992-11-10
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Expires: 2012-04-13
Abstract
Abstract A thermal printer includes motor control apparatus for variably controlling the rotational speed of a take-up spool used to wind-up an expended dye-bearing donor web after passage through a print zone. The donor web is moved through the print zone at a substantially constant velocity by a rotatably driven print drum which cooperates with a thermal print head to unwind the donor web from a supply spool. The motor control apparatus operates to rotate the take-up spool at a speed inversely proportional to the instantaneous take-up spool diameter, whereby the expended donor web is accummulated at a rate slightly slower than the rate at which it is payed-out of the print zone during the printing operation. Preferably, the desired rate of rotations of the take-up spool, which gradually decreases with the number of prints made, is determined by the use of a shaft encoder mounted on the support shaft of the supply spool. During the production of thermal prints, the output of such shaft encoder is used to control a variable speed motor which appropriately decreases the rotational velocity of the take-up spool to maintain a zero tension in the web between the print zone and take-up spool. By eliminating tension on the donor web during printing, certain tension-produced artifacts in the thermal print are avoided.
Inventors
- 👤 Donald J. Hodge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:32
CPC Classifications
B; B41; B41J; B41J17/00; B41J17/02; B41J17/08; B41J17/10
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
202 words
A method for producing thermal prints comprising: unwinding a dye-bearing donor web from a rotating supply spool and advancing such donor web to a print zone at which such web is acted upon by a thermal print head and print drum to transfer dye from the web to a print-receiving medium; advancing such donor web from the print zone toward a take-up spool by controllably rotating said print drum by a first motor means, said take-up spool having an instantaneous web diameter and being rotatable at a rotational speed; winding up the advanced donor web on the take-up spool by rotatably driving the take-up spool by a second motor means; producing a signal proportional to the number of rotations of the supply spool as the web is unwound therefrom; and using such signal to control the rotational speed of the take-up spool so that, while dye is being transferred to the print medium at the print zone, the take-up spool rotates at a speed inversely proportional to the take-up spool diameter and the web is wound upon the take-up spool at a slower rate than said web is paid-out of the print zone to thereby eliminate tension on said web during printing.
Claim 2
Independent Claim
202 words
A method for producing thermal prints comprising: unwinding a dye-bearing donor web from a rotating supply spool and advancing such donor web to a print zone at which such web is acted upon by a thermal print head and print drum to transfer dye from the web to a print-receiving medium; advancing such donor web from the print zone toward a take-up spool by controllably rotating said print drum by a first motor means, said take-up spool having an instantaneous web diameter and being rotatable at a rotational speed; winding up the advanced donor web on the take-up spool by rotatably driving the take-up spool by a second motor means; producing a signal proportional to the number of rotations of the supply spool as the web is unwound therefrom; and using such signal to control the rotational speed of the take-up spool so that, while dye is being transferred to the print medium at the print zone, the take-up spool rotates at a speed inversely proportional to the take-up spool diameter and the web is wound upon the take-up spool at a slower rate than said web is paid-out of the print zone to thereby eliminate tension on said web during printing.
Claim 3
Dependent Claim
76 words
The apparatus as defined by claim 1 wherein said supply spool has a rotational velocity, and wherein said signal-producing means comprises a shaft-encoder operatively coupled to said supply spool, said shaft-encoder being adapted to provide an output signal in the form of a series of pulses occurring at a rate proportional to the rotational velocity of said supply spool, means for counting said pulses, and means for producing an analog signal proportional to the pulse count.
Claim 4
Dependent Claim
196 words
Thermal printing apparatus comprising: a supply spool having thereon a dye-bearing donor web; means for rotatably supporting said spool; a rotatably-driven print drum for unwinding such web from said supply spool and for advancing such web past a thermal print head at a print zone where dye is transferred to a print-receiving medium by said print head, said rotatably-driven print drum causing said supply spool to rotate as it unwinds web therefrom and further causing the web to be paid-out of the print zone at a constant rate; first motor means for rotating said print drum; a rotatably-mounted take-up spool for accumulating web paid-out of said print zone; means for producing a signal proportional to the number of revolutions of said supply spool as web is unwound therefrom; and variable-speed motor means, responsive to said signal, for rotating said take-up spool at a variable rate such that, during printing, the speed of rotation of the take-up spool decreases as donor web is accumulated and the take-up spool accumulates the donor web at a slower rate than the rate at which it is paid-out of said print zone to thereby eliminate tension on said web during printing.
Claim 5
Dependent Claim
196 words
Thermal printing apparatus comprising: a supply spool having thereon a dye-bearing donor web; means for rotatably supporting said spool; a rotatably-driven print drum for unwinding such web from said supply spool and for advancing such web past a thermal print head at a print zone where dye is transferred to a print-receiving medium by said print head, said rotatably-driven print drum causing said supply spool to rotate as it unwinds web therefrom and further causing the web to be paid-out of the print zone at a constant rate; first motor means for rotating said print drum; a rotatably-mounted take-up spool for accumulating web paid-out of said print zone; means for producing a signal proportional to the number of revolutions of said supply spool as web is unwound therefrom; and variable-speed motor means, responsive to said signal, for rotating said take-up spool at a variable rate such that, during printing, the speed of rotation of the take-up spool decreases as donor web is accumulated and the take-up spool accumulates the donor web at a slower rate than the rate at which it is paid-out of said print zone to thereby eliminate tension on said web during printing.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-11-10 | 1996-05-11 | 1996-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-11-10 | 2000-05-11 | 2000-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-11-10 | 2004-05-11 | 2004-11-10 | $7700.00 | Window Closed / Lapsed |